Correlation between phase formation and magnetic properties of heavy ion irradiated Co/Pt bilayers

In this letter, the authors report the correlation between the magnetic and the structural properties of 200keV Kr and 50keV Ar ion irradiated Co∕Pt bilayer samples at different temperatures and fluences. They observe irradiation induced formation of stable Co–Pt phases, which appears to be more prominent at higher irradiation temperatures. A large shape anisotropy in the hysteresis loop is also observed when irradiated at higher temperatures, which could be indicative of a magnetization reversal. A CoPt ordered/disordered phase formation leads to the enhancement in the coercivity. The sequence of phase formations is predicted by the heat of formation rule.